We haven't run out of gas...yet...
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| Official statistician |
tldr;
We haven't "run out of gas"
Model X90D pulling trailer 485Wh/mi (early estimate for flat and 55mph)
Estimated range pulling trailer 170 miles
Long version
We haven't "run out of gas"...yet
When taking a trip in an electric vehicle, or any vehicle for that matter, it's important to know you can make it to the next gas station (or charging opportunity in our case). I've been driving electric for almost ten years. From short trips around town to long trips as far as Maine and North Carolina. I've never "run out of gas".
What's different with this trip is pulling a trailer decreases "gas mileage" and range between charges. How much of a range hit we'll take traveling back is the big unknown. There are not a lot of people pulling trailers with electric vehicles. Different trailers affect range differently. Weather, speed, and elevation changes all affect range.
There are several tools that can help with trip planning. EV Trip Planner and A Better Route Planner are two online planners. There is also Tesla's own in vehicle navigation system.
The first two rely on you inputting the actual "gas mileage" pulling the trailer (the number I'm making an estimated guess). The later estimates the "gas mileage" based on recent driving and re-calculates the range as you drive, based on it's recent estimates.
A recurring theme in all of the above is estimate and guess. Two words you really don't want to rely on when the nearest charger is 125 miles away, you have to pass over a 10000 ft pass, in the rain, with headwinds!
So with that in mind here are how the guestimates have been working out so far.
Trip out (no trailer)
Overall EVTripPlanner did a pretty good job of calculating energy consumption. This would be expected since Tesla provides the EPA with energy consumption numbers. And there are plenty of Model X's on the road for real world data.
As for our actual energy consumption it did underestimate consumption by around 10% (8-13% on average). But that's not horrible. For example if it said we would arrive at the next charging station with 40 miles remaining, we would on average end up arriving with 36 miles remaining. This is no different than a gas car where the EPA says it gets 40MPG but you only get 36MPG.
We haven't "run out of gas"
Model X90D pulling trailer 485Wh/mi (early estimate for flat and 55mph)
Estimated range pulling trailer 170 miles
Long version
We haven't "run out of gas"...yet
When taking a trip in an electric vehicle, or any vehicle for that matter, it's important to know you can make it to the next gas station (or charging opportunity in our case). I've been driving electric for almost ten years. From short trips around town to long trips as far as Maine and North Carolina. I've never "run out of gas".
What's different with this trip is pulling a trailer decreases "gas mileage" and range between charges. How much of a range hit we'll take traveling back is the big unknown. There are not a lot of people pulling trailers with electric vehicles. Different trailers affect range differently. Weather, speed, and elevation changes all affect range.
There are several tools that can help with trip planning. EV Trip Planner and A Better Route Planner are two online planners. There is also Tesla's own in vehicle navigation system.
The first two rely on you inputting the actual "gas mileage" pulling the trailer (the number I'm making an estimated guess). The later estimates the "gas mileage" based on recent driving and re-calculates the range as you drive, based on it's recent estimates.
A recurring theme in all of the above is estimate and guess. Two words you really don't want to rely on when the nearest charger is 125 miles away, you have to pass over a 10000 ft pass, in the rain, with headwinds!
So with that in mind here are how the guestimates have been working out so far.
Trip out (no trailer)
Overall EVTripPlanner did a pretty good job of calculating energy consumption. This would be expected since Tesla provides the EPA with energy consumption numbers. And there are plenty of Model X's on the road for real world data.
As for our actual energy consumption it did underestimate consumption by around 10% (8-13% on average). But that's not horrible. For example if it said we would arrive at the next charging station with 40 miles remaining, we would on average end up arriving with 36 miles remaining. This is no different than a gas car where the EPA says it gets 40MPG but you only get 36MPG.
So numbers for the way out were:
Miles traveled 2700 miles
Actual rated miles used 12-14% higher than predicted
Actual energy used (kWh) 5% higher that predicted
Actual Wh/mi 8-13% higher than predicted (avg 350 vs avg 323)
Trip back (early results)
To date we've pulled the Tin Poodle just over 425 miles. This includes an elevation change of 4400 ft (going up).
Based on reports here, here, and here I used a "guestimate" of 515-520 Wh/mi as the energy consumption for pulling the trailer. This assumed flat ground and 55 mph speed limit. I then used this number as the "MPG" on EVTripPlanner to come up with a real world trailer prediction for the return trip.
For the first legs of of this trip the model predicted energy consumption of 543 wH/mi. Actual consumption for these legs was 510 Wh/mi. A six percent improvement over the estimate.
As I mentioned earlier was over terrain with significant altitude gains. Extrapolating to flat ground the six percent improvement would give an estimate on flat ground of 485Wh/mile. This equates to a range of approximately 170 miles on flat ground while pulling the Bowlus. Not bad compared to the 254 mile flat ground range without a trailer.
A few caveats
When pulling the trailer, especially on stretches with altitude gain, I tend to start conservatively. This means speeds of 50-55 mph. After about 25% into the leg until the next supercharger I'll evaluate consumption. As long as the Tesla trip planner is not showing a drop in expected range I'll increase speed to 55-60 mph (if the limit is > 55mph). Finally if after about 65% of the way to the next supercharger range predictions are holding then I'll increase to up to 62-64 mph.
On a future post I'll get into more detail about the energy consumption trip planner software included with every Tesla.
Trip back (early results)
To date we've pulled the Tin Poodle just over 425 miles. This includes an elevation change of 4400 ft (going up).
Based on reports here, here, and here I used a "guestimate" of 515-520 Wh/mi as the energy consumption for pulling the trailer. This assumed flat ground and 55 mph speed limit. I then used this number as the "MPG" on EVTripPlanner to come up with a real world trailer prediction for the return trip.
For the first legs of of this trip the model predicted energy consumption of 543 wH/mi. Actual consumption for these legs was 510 Wh/mi. A six percent improvement over the estimate.
As I mentioned earlier was over terrain with significant altitude gains. Extrapolating to flat ground the six percent improvement would give an estimate on flat ground of 485Wh/mile. This equates to a range of approximately 170 miles on flat ground while pulling the Bowlus. Not bad compared to the 254 mile flat ground range without a trailer.
A few caveats
When pulling the trailer, especially on stretches with altitude gain, I tend to start conservatively. This means speeds of 50-55 mph. After about 25% into the leg until the next supercharger I'll evaluate consumption. As long as the Tesla trip planner is not showing a drop in expected range I'll increase speed to 55-60 mph (if the limit is > 55mph). Finally if after about 65% of the way to the next supercharger range predictions are holding then I'll increase to up to 62-64 mph.
On a future post I'll get into more detail about the energy consumption trip planner software included with every Tesla.
I would like to see how EV Trip Optimizer (iOS app) does predicting your travels using the "Model X High Profile" setting.
ReplyDeleteloving this
ReplyDeleteI can’t drive 55. Aside from that the estimates are looking fairly close :)
ReplyDelete